1. Field of the Invention
The present invention pertains to optoelectronic devices or optical subassemblies. The invention more particularly concerns a small format optoelectronic package.
2. Discussion of the Background
Optoelectronic devices such as optical transceivers are known in the art and include active optical devices or diode packages. Common diode packages include LED packages such as a TO-46 package or a 5.6 mm TO style laser diode package such as an RLD-85PC diode package by Rohm, Incorporated. These diode packages or TO cans typically include a metallic housing having a laser diode or LED for transmitting data and a photo diode for performing power-monitoring, metal contact leads exiting from the diodes for connection to a power source and a cover glass opposed to the diode, through which the energy is transmitted. Discussion of the power-monitoring and feedback control of the laser diode by the photo diode is presented in U.S. Pat. Nos. 5,812,582 and 5,815,623. U.S. Pat. Nos. 5,812,582 and 5,815,623 are hereby incorporated herein by reference. The TO can is hermetically sealed. Often, optics housings arc metallic so as to provide ruggedness, ease of machining complicated shapes, and to enhance shielding of electromagnetic fields.
Smaller optoelectronic packages allow the devices into which the optoelectronic packages are placed to become smaller. Smaller optoelectronic packages allow for a higher density of data transmission in a given space. Currently, the re is a great demand for smaller optoelectronic packages.
FIG. 8 is a partial cross-sectional pictorial view of an optoelectronic package 200. The optoelectronic package 200 includes a base element 212, posts 206, 208, 210, extending through the base element 212 and secured thereto with solidified molten glass 214, a monitor diode 204 mounted on the base element 212, an optical emitting element 202 mounted on the monitor diode 204, a can 218 and lens 216 enclosing the monitor diode 204 and the optical emitting element 202. In an effort to reduce space, the optical emitting element 202 is mounted on top of the monitor diode 204. Electrically conductive posts 206, 208, 210 extend through through-holes in the electrically conductive base element 212. The posts 206, 208, 210 arc electrically insulated from the base element 212 by solidified molten glass 214 which also attaches the posts 206, 208, 210 to the base element 212. The posts 206, 208, 210 arc large as compared to the other components and require a large area for the ir mounting and placement.
At minimum, the diameter across the base element 212 is approximately 3.8 millimeters, as incorporated on the SLT2160-LN series of transmitter optical sub-assemblies manufactured by Sumitomo Electric Industries, Ltd. Thus, if two of the se devices are placed side-by-side, on the same plane, the distance between the optical axes is, hypothe tically, at best, 3.8 millimeters. However, typically, the optical axes are separated by 6.25 millimeters, due to packaging constraints as in typical LC duplex transceivers such as Methode Electronics, Inc.'s, part number MLC-25-4X-TL which is described in the data sheet entitled, "MLC-25-4-X-TL Optical Gigabit Ethe rnet -+3.3V Small Form Factor (SFF) Transceiver -1.25 GBaud."
Therefore, the re is a need in the industry for a small format optoelectronic package that has a small diameter and is easy to manufacture. Furthe rmore, the re is a need for an optoelectronic package that can be placed adjacent to another optoelectronic package.